English: Tết Nguyên Đán, more commonly known by its shortened name Tết, is the most important and popular holiday and festival in Vietnam. It is the Vietnamese New Year which is based on the Chinese calendar, a lunisolar calendar. The name Tết Nguyên Đán is Sino-Vietnamese for Feast of the First Morning, derived from the Hán nôm characters 節元旦. In modern Chinese, the characters for Nguyên Ðán (元旦) have evolved to refer to New Year in the Gregorian calendar, that is, January 1